Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body in which the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to certain organs (e.g. in thyroiditis) or involve a particular tissue in different places (e.g. Goodpasture's disease which may affect the basement membrane in both the lung and the kidney). The treatment of autoimmune diseases is typically with immunosuppression—medication which decreases the immune response. The mechanisms of autoimmune diseases are not well understood and the treatment options are limited.
Examples of autoimmune diseases include Coeliac disease, diabetes mellitus type 1 (IDDM), systemic lupus erythematosus (SLE), Sjögren's syndrome, Churg-Strauss Syndrome, Hashimoto's thyroiditis, Graves' disease, idiopathic thrombocytopenic purpura, and rheumatoid arthritis (RA).
Sjögren's syndrome (SjS) is a chronic autoimmune inflammatory disease characterized by lymphocytic infiltration and destruction of lacrimal glands (LG) and salivary gland function (SG). SjS can occur independently (primary SjS) or in conjunction with another autoimmune disease (secondary SjS); both forms may progress to systemic disease of other organs. In both primary and secondary SjS, the presenting symptoms of ocular surface dryness, corneal irritation and increased susceptibility to infection overlap with symptoms of simple keratoconjunctivitis sicca (KCS). Despite the potentially unique disease profile that is likely to be manifested in the tears of primary and secondary SjS patients, no tear biomarkers have been established as diagnostic for either form.
Definition of tear biomarkers which can predict disease severity would be valuable diagnostically in combination with existing clinical strategies, potentially contributing to different choices of therapy and improved disease outcome for SjS as well as for other autoimmune diseases. Since sensitivity of detection and stability of biomarkers and detection reagents are significant challenges given the limited sample sizes and extensive protease content of even normal tears, development of alternative detection strategies for tear biomarkers is clearly warranted. This invention satisfied this need and provides related advantages as well.